Early apparatus for testing telephone circuits were manually operated individual routing test sets capable of testing only isolated parts of the signalling path in out-of-traffic or simulated traffic conditions. An improvement on these manual test devices was subsequent automatic digital test systems which decoded and displayed the progress of test calls and actual traffic.
Due to complexity and diversity of present day telephone systems it is desirable to have testing devices to match. The increasing international direct dial telephone and Telex traffic, for instance, utilizes a variety of signalling formats, dependent on the international boundaries it crosses.
A typical telephone call placed from, say, England to North America may be set up after utilizing signalling schemes such as: dial pulsing, single-tone pulsing, pulsed multifrequency, non-compelled multifrequency (CCITT5) and E&M line signalling.
It is therefore an object of the present invention to provide an integrated signalling test apparatus to monitor diverse signalling conditions particularly during live traffic.
According to the present invention there is provided signalling test apparatus for monitoring a voice frequency telephone line and the like comprising: interface means for accessing said telephone line in parallel without disturbing its normal operation; a plurality of modules responsive to said interface means for analyzing signalling intelligence including d-c conditions on said telephone line; control and storage means responsive to said plurality of modules for storing and displaying results of signalling analysis performed by said modules.
In a narrower aspect of the present invention, the module for signalling analysis includes a signalling analysis portion and a digital interface portion; the latter including a read-only-memory for storing information identifying said module and defining validity criteria for the signalling intelligence as well as means including signal conversion means for translating the signalling intelligence into a form or mode compatible with said control and storage means.